1. Field of the Invention:
The present invention relates to an apparatus and method for sampling and analyzing impurities in hygroscopic liquids having a purity of more than 99.95% by weight. The present invention also relates to an apparatus and method for the quantitative, infra red spectroscopic (IR-spectroscopic) determination of impurities in hygroscopic liquids having a purity of more than 99.95% by weight.
2. Discussion of the Background:
High-purity products such as silicon tetrachloride are presently used, inter alia, in the production of optical fibers. The analytical methods employed in the quality control of high-purity liquids should correctly reflect the actual purity of the product. Particularly during sampling, additional impurities (e.g., moisture) might be introduced which may cause secondary reactions.
Conventionally, the impurities in silicon tetrachloride are determined quantitatively by IR spectroscopy. This process is described, for example, in Anal. Chem. 1987, 59, 1089-1093 and Anal. Chem. 1981, 53, 1967-1968.
Also, it is known that TEFLON-coated cells or cells made of stainless steel together with AgCl windows can be used for sampling and analysis in laboratories. However, in practice, undesired impurities might be introduced before the actual measurement when using the known methods and cells on an industrial scale.